Relay system and method



Dec. 1, 1931. F. A/KOLSTER 1,334,233

RELAY SYSTEM AND METHD Filed Sept. 12, 1928 INVENTOR.

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Patented Dec. 1, 1931 UNITED STATES PATENT I OFFICE. I J

' FREDERICK A. KOLSTER, OF PALO ALTO; CALIFORNIA, ASSIGNOR 'I O FEDERAL TELE- GRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF. CALI- 5 for use with electron relay amplifiers,

FORNIA RELAY SYSTEM AND neuron Application filed September 1 1928. 'Serial No. soa n'o This invention relates generally to relay systems and methods of operating the same for repeating and amplifying current variations. It is particularly applicable for repeating and amplifying currents of radio frequency employed in signalling systems.

It is an object of this invention to devise a novel form of relay system and method whereby positive feed back coupling between the output and input circuits can be balanced out to prevent generation of local oscillations.

It is a further object of this invention to devise a novel form of neutralizing system which is characterized by the fact that the reactive output circuit of the relay is completed by a connection to the relay input circuit.

It isa further object of this invention to devise a neutralizing system for electron relays characterized by operation of the oathode of the relay at a potential difieringfrom ground potential. v

Further objects of the invention will appear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that the appended claim is to be accorded a range of equivalents consistent with the-state of the prior art.

Referring to the drawings:

Fig. 1 is a simplified circuit diagram illustrating certain principles of my invention.

Fig. 2 is a circuit diagram illustrating my invention applied to the electron relay amplifier of a system.

When using electron relays for amplifying current variation, it is generally desirable to provide means for preventing generation of local oscillations due to positive feed back coupling between the output and input circuits. My invention makes possible this re sult in a novel and simplified way, and with out the use of additional reactances other 0 than those ordinarily employed in the input and output circuits. 7

The principles of my invention can best be explained by referenceto Fig. 1, in which I have shown an electron relay consisting of the usual grid or control element 11, plate'or.

circuit of the relay, ing ClIClllt 22,w1ll cause no corresponding anode 12, and cathode 13. The input circuit is formed by inductance 14, having one point thereof connected to) grid 11, and another .point connected to cathode 13'. The output or plate circuit includes inductance 16 having one point thereof connected to plate 12. Conductor 17 which is generally employed for completing the output circuit, has been shown connected to a tap 18. on inductance 14,

rather than directly to 'cathode13. For convenience I have indicated a'measuring device 19 inserted in series with conductor17.

Ordinarily with acircuit arrangementsuch as described above, the electron relay because of its construction provides capacitances between its elements which can be represented by condensers 1, 2 and 3. One or more of these ca-pacitances ordinarily serve to re actively couple the output to'the input so u that positive feed back ofenergy is provided. Thusbecause of such positive feed back .the

ordinary amplifier .relay system tends {to oscillate locally, particularly if'the input and output circuits are tunedto the same radio frequency. v .1

Assuming that oscillations can be induced in the output circuit of the relay, as ,for

example, by an oscillator circuit 21 inductively related to inductance thru ,conductor17 tends to divide into two reactive paths provided by inductance and completed thru the inter-electrode I capaci- By adjusting the position tance of the relay.

of tap 18, it is possible to balance the two that no corresponding pobetween the grid 11 reactive paths so te'ntiall differences occur and cathode 13. In 0 her words the relay and associated circuits can be caused to form a bridge circuit in which grid lland cathode 13 are at points neutral with respect to each other. When the properposition for tap'18 has been'found, oscillation set up to the input as by means of an excitcurrent flow to occur thru'conductor 17. V

One manner in which'the principles outlined above can be used in practiceis'shown in Fig. 2. In this case both inductances 141- and 16 are tuned by means ofcond'ensers 23 and 24. A blockingcondenser '26 is employed 16, energy. introduced in series with the plate circuit, and an operating anode potential is maintained upon the plate from a suitable source of current represented by B battery 27 the negative termi- 5 nal of this battery being shown connected to groundjfi, while the positiveterminal is connectedito the platethru a suitable high frequency choke 29. Means is also shown for maintaining a negative bias upon the grid of the relay, and .wlnchln this case utilizesgri'd' condenser 3:1 andgrid leak resistance'32connected to the ground in series with high frequency choke 33. The cathode -for-the. relay is of the usual filament type, excited from a suitable source of current represented by the step-down alternating .current transformer 34:. The output terminalsof this transformer are connected to theterminalsof the filament thru high .frequencychokes 36, in order to permit the cathode to operate at a potential differing from ground potential. The lead 37 for completing the grid circuit oftherelay is'connected to the mid point of an impedance placed across the terminals of the 2. cathode. Such an impedance can be formed by a pair-.of condensers 38. As in the ease of Fig. 1, the tuned plate circuit iscompleted thru lead 17 connected-to tap 18 upon inductance 1.6. The input circuit issupplied with .0 high frequency oscillations from asuitable source represented by circuit 39, while the output circuit supplies a load representedby the radio antenna circuit 4'1.

in operating the system of Fig.2, the positionof tap 18 is adjusted until the relay repeats and amplifies the high frequency oscillations without continuing in oscillatory condition afterexcitation of the grid eircuithas ceased. VV'hen so adjusted positive coupling $0 from the output to the input of the relay which would ordinarily cause .corresponding potential differences between the grid and the cathode, no longer causes such variation and therefore .cannot cause generation of local oscillations. The cathode 13 operates at potentials differing. from ground potential. WVhen amplifying high frequency oscillations an appreciable current flow occurs through lead 17.

150 I claim Ina translating system, an inputcircuit, an output circuit, and: a translating device having an input electrode, anoutputelectrode and a common inputand output electrode,

.55 said input circuit comprising at least one impedance element connected betwcensaid input electrode and said common electrode, andsaid output circuit being connected between said output electrode and a tap on said input cir- -cuit at such a point that the ratio of theimmy hand.

F REDER QK A. ,KOLS'EER. 

